Thick, Printable Labels Suitable for Use in a Thermal Transfer Printer

ABSTRACT

Thick, compressible, multilayer labels with the appearance and feel of hard plastic identification shields comprise:
         A. A printable film having first and second opposing facial surfaces;   B. A first adhesive having first and second opposing facial surfaces, the first facial surface of the adhesive in intimate contact with the second facial surface of the film; and   C. Foam having first and second opposing facial surfaces, the first facial surface of the foam in intimate contact with the second facial surface of the first adhesive.
 
In certain embodiments of the invention, the labels include one or more of a printable coating on the first facial surface of the film, a second adhesive in intimate contact with the second facial surface of the foam, and a release liner in contact with the second adhesive.

FIELD OF THE INVENTION

This invention relates to printable labels. In one aspect, the inventionrelates to thick, printable labels adapted for use in thermal transferprinters while in another aspect, the invention relates to thick,printable labels useful as a replacement for engraved or plottedidentification shields. In yet another aspect, the invention relates toa method of making thick, printed labels using thermal transferprinters, particularly handheld thermal transfer printers.

BACKGROUND OF THE INVENTION

In the industrial world, panel and machine builders use many pushbuttons and signal lights. These buttons, lights, panels, closets andthe like are identified by various means. One such means is hard-plasticidentification shields. These shields typically consist of arectangular, hard-plastic plate that can be plotted, engraved orpreprinted by the supplier. “Hard-plastic” means that the plate is stiffand exhibits little, if any, flexibility. The shields or plates areeither self-adhesive or mechanically mounted on or about the panel,closet, button, etc. Often these shields are used in combination with ashield or plate holder.

The use of hard-plastic identification shields has a number ofdisadvantages. If the shields are to be kept in stock, then this canresult in the creation and maintenance of a large shield inventory,especially if the shields vary in color, legend and size. If the shieldsare to be created as needed, then expensive and often operationally slowplotting and/or engraving equipment must be acquired and maintained(options that are often economical only for large panel applications).Outsourcing the task of creating plotted and/or engraved plates can alsobe expensive and time consuming.

One alternative to hard-plastic identification shields is a printablelabel that can be processed in standard printing equipment. Typically,the labels are attached to a carrier strip, fed into a printer, andimprinted with a legend. The labels are then removed from the carrierand attached to or about the objects requiring identification. Becauseof the limitations of the printers, theses labels tend to be thin andflexible and thus lack the feel and appearance of hard-plasticidentification shields. However, printable labels are a well-recognizedsolution to the problems associated with hard-plastic identificationshields, particularly with respect to cost and inventory.

One particularly useful class of printers for creating printed labels isthe type that employs thermal transfer (THT) printing technology. Ofthese printers, hand-held THT printers are particularly desirable due totheir low cost (relative to desktop printers), portability andease-of-use. THT printing uses a heat generating print head to transferan ink layer (typically a wax and/or other binder compounded with carbonblack and/or other pigment) or the like, from a THT ribbon to a label.By using digital technology, characters are formed on a label byenergizing a sequence of pixels on the print head and when the printhead comes in contact with the ribbon, it softens the wax and/or otherbinder of the ink layer on the ribbon. At the same time that the printhead is in contact with the ribbon, the ribbon is in contact with thelabel, and thus the character image on the print head is transferred tothe label.

THT label printers use a labeling media that is fed from a media unwindsimultaneously when a platen roll feeds it and an ink transfer ribbon.The labeling media and the transfer ribbon pass between the print headand the platen, driven by the rotating platen. As a result, the labelingmedia and the transfer ribbon pass together in overlay relationshipbetween the print head and the platen roll. These printers and theiroperation are described more fully in U.S. Pat. Nos. 5,951,177,6,113,293 and 6,769,825.

The use of thick, i.e., greater than (>) about 300 microns (:m),labeling media in many commercially available THT printers, particularlyhand-held printers, is problematic at best. Most commercially availableTHT printers are designed to process labeling media no thicker thanabout 300 :m, and such labels are far removed from the hard-plasticshields in terms of appearance and feel (or heft). Accordingly, thelabeling industry has a recognized need for labels that have theappearance and feel of hard-plastic identification shields but that canbe printed using a THT printer, particularly a hand-held THT printer.

SUMMARY OF THE INVENTION

According to this invention, a thick, compressible, multilayer labelthat is suitable for use with conventional, commercially available THTprinters, particularly hand-held printers, is described. In a firstembodiment of this invention, the label comprises:

A. A printable film having first and second opposing facial surfaces;

B. A first adhesive having first and second opposing facial surfaces,the first facial surface of the adhesive in intimate contact with thesecond facial surface of the film; and

C. Foam having first and second opposing facial surfaces, the firstfacial surface of the foam in intimate contact with the second facialsurface of the first adhesive.

In a second embodiment of the invention, the label further comprises:

D. A coating in intimate contact with the first facial surface of thefilm.

In a third embodiment of the invention, the label further comprises:

E. A second adhesive having first and second opposing facial surfaces,the first facial surface of the second adhesive in intimate contact withthe second facial surface of the foam.

In a fourth embodiment of the invention, the label further comprises:

F. A release liner having first and second opposing facial surfaces, thefirst facial surface of the liner in intimate contact with the secondfacial surface of the second adhesive.

In the first embodiment, the film comprises any material suitable foruse as a substrate to receive and hold an image from a printer, e.g., apolymeric material that will receive and hold an ink layer from atransfer ribbon of a THT printer. In the second embodiment, the coatingcan either serve as the substrate to receive and hold the image from theprinter (in which case the film can but need not comprise a materialadapted for such a use), or it can serve as a protective covering forthe film and/or image (in which case the film is adapted to receive andhold the image). In another variation on this combination of coating andfilm, the coating can serve as a substrate to receive an image from theprinter and as a protective covering for the film.

In each embodiment of the invention, the label construction, i.e., thecombination of the film, first adhesive and foam, and optionally thecoating, second adhesive and/or release liner, is greater than about300, typically greater than about 400, more typically greater than about500 and even more typically greater than about 600, :m. The individualthickness of each component or layer of the label construction can varywidely, but typically the foam layer is the thickest part of theconstruction. The foam is sufficiently compressible such that the labelconstruction can be fed through and a legend printed upon the filmand/or printable coating in a printer, preferably a THT printer, andmore preferably a THT hand-held printer.

In another embodiment the invention is label media, i.e., labels on acarrier strip that usually doubles as a release liner, on which thelabels are positioned in such a manner that the media can be fedcontinuously through a printer, preferably a THT printer and morepreferably a THT hand-held printer, without deleterious back feeding. Inthis embodiment, the labels are placed on the carrier strip such thatthe space or gap between adjacent labels on the strip is small relativeto the diameter of the platen roller such that the print head is notpressed too far into the space or gap between the labels. In yet anotherembodiment, the invention is label media in which filler strips or thelike bridge the gap (or at least enough of the gap) between adjacentlabels such that the print head is not pressed into the gap.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross section of the first embodiment of theinvention.

FIG. 2 is a schematic cross section of the second embodiment of theinvention.

FIG. 3 is a schematic cross section of the third embodiment of theinvention.

FIG. 4 is a schematic cross section of the fourth embodiment of theinvention.

FIG. 5 is a schematic depiction of one embodiment of the label media ofthis invention.

FIG. 6 is a schematic depiction of another embodiment of the label mediaof this invention.

FIG. 7 is a schematic depiction of another embodiment of the label mediaof this invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic cross section of the first embodiment of theinvention. The construction of this embodiment is a three-layerstructure comprising a first or top layer of film 10 in intimate contactwith a second or intermediate layer of first adhesive 11 that in turn isin intimate contact with third or bottom layer of foam 12. “In intimatecontact” means that two facial (as opposed to edge) surfaces of theadjoining layers are in contact with one another as is a coating withits substrate. While preferably the full facial surface of one layer isin intimate contact with at least part of the adjoining facial surfaceof the other layer (e.g., one layer has a smaller facial surface areathan the other layer), “in intimate contact” also includes thosevariations in which only part of one facial surface of one layer is incontact with only part of the adjoining facial surface of the otherlayer, e.g. the adhesive layer is a series of adhesive islands on thesecond facial surface of the film.

In this first embodiment, second facial surface 10 b of film 10 is inintimate contact with first facial surface 11 a of first adhesive 11,and second facial surface 11 b of first adhesive 11 is in intimatecontact with first facial surface 12 a of foam 12. First facial surface10 a of film 10 is available to receive and hold an image from either aprinter or other image-transferring device (not shown), or coating 13 asdepicted in FIG. 2, and second facial surface 12 b of foam 12 isavailable to intimately join with first facial surface 14 a of secondadhesive 14 as depicted in FIG. 3.

FIG. 2 is a schematic cross-section of the second embodiment of theinvention. The construction of this embodiment is a four-layer structurecomprising the three-layer structure of the first embodiment incombination with printable coating 13. In this embodiment, second facialsurface 13 b of coating 13 is in intimate contact with first facialsurface 10 a of film 10, coating 13 thus being the top layer of thislabel construction. As the top layer, first facial surface 13 a ofcoating 13 is available to receive and hold an image from either aprinter or other image-transferring device (not shown).

FIG. 3 is a schematic cross-section of the third embodiment of theinvention. The construction of this embodiment is at least a four-layerstructure comprising the three-layer construction of the firstembodiment in combination with second adhesive 14, optionally in furthercombination with coating 13. In this embodiment, second facial surface12 b of foam 12 is in intimate contact with first facial surface 14 a ofsecond adhesive 14. If coating 13 is present as depicted in FIG. 2, thenthe label construction of this third embodiment comprises five layers;if the coating 13 is not present, then the label construction of thisthird embodiment comprises four layers. Preferably coating 13 is presentin this embodiment.

FIG. 4 is a schematic cross-section of the fourth embodiment of theinvention. The construction of this embodiment is at least a five-layerstructure comprising the three-layer construction of the firstembodiment in combination with second adhesive 14 and release liner 15,optionally in further combination with coating 13. In this embodiment,second facial surface 14 b of second adhesive 14 is in intimate contactwith first facial surface 15 a of release liner 15. If coating 13 ispresent as depicted in FIGS. 2 and 3, then the label construction ofthis fourth embodiment comprises six layers; if the coating 13 is notpresent, then the label construction of this fourth embodiment comprisesfive layers. Preferably coating 13 is present in this embodiment. Secondfacial surface 15 b of release liner 15 is typically exposed to theenvironment and is constructed of such materials and in such a manner toallow the label construction of this embodiment to be formed into a rollthat will exhibit little, if any, blockage upon unraveling andsufficient coefficient of friction with the platen roll to minimizeslippage when driven.

The film used in the label constructions of this invention can compriseany material that will either or both receive and hold an imagetransferred from a printer or other image-transferring device or supporta coating that can receive and hold an image transferred from a printeror other image-transferring device. Typically, the film is made from apolymeric material such as polyester (e.g., polyethylene terephthalate(PET)), polyolefin (e.g., polyethylene, polypropylene, etc.),polycarbonate and the like. The thickness of the film is typically atleast about 100, preferably at least about 150 and more preferably atleast about 200, :m. In one embodiment, two or more films, e.g., two ormore polyester films, are heat-laminated together to produce amultilayer film of a desired thickness. Thermfilm DM/M-800, a multilayerpolyester film manufactured and sold by Flexcon Company isrepresentative of this kind of film. The film is sized and designed toprovide the appearance and feel of a hard-plastic shield afterapplication to a substrate surface.

The foam used in the label constructions of this invention can compriseany material that will compress sufficiently to allow the label to befed through a printer or other image-transferring device, preferably aTHT printer and more preferably a THT hand-held printer, and that willregain most, if not all, of its original thickness upon or shortly afterexiting the printer or device. Typically the foam comprises a polymericmaterial, and preferably it comprises a polyethylene or polyurethanematerial. Polyethylene foams are particularly preferred. The thicknessof the foam layer is typically at least about 200, more typically atleast about 300 and most typically at least about 350, :m.

The first and second adhesives can be the same or different, as eachserves a different purpose than the other. The purpose of the firstadhesive is to provide a permanent bond between the film and the foamand as such, can be either a pressure sensitive adhesive or aheat-sealable adhesive. The purpose of the second adhesive is to providea means for fixing the label once printed to a surface where it canserve as an identification marker and as such, preferably the secondadhesive is a pressure-sensitive adhesive.

The adhesives that can be used in the practice of this invention can beof various types available for the intended purpose. Heat-sealableadhesives are commonly available in solution or emulsion form and can bedirectly coated on the underside of the film (surface 10 b in FIG. 1),or the top side of the foam (surface 12 a in FIG. 1), or heat laminatedto either surface, or heat laminated between each surface in oneprocess. If the heat-sealable adhesive is first coated or laminated toone surface, then the other surface is heat laminated to complete thetop part of the construction. Various adhesives types can be used forthis lamination including polyesters and modified synthetic elastomers.

In the case of the use of pressure-sensitive adhesives either forlamination of the film to the foam or for mounting the product (surface12 b in FIG. 3), any of the types available either as coatings bysolution, emulsion, hot melt, uv-curable, etc., can be used along withpre-cast pressure-sensitive adhesives (commonly known as transferadhesives). In the case of direct coating, the adhesive is applied tothe foam surface and if required a release liner (15 in FIG. 4) islaminated to it. In the case of a transfer adhesive, the pre-castadhesive is laminated to the foam, generally including a liner which canbe used (as 15 in FIG. 4) if suitable, or removed and replaced with amore suitable liner. Pressure sensitive adhesives are compounded fromvarious polymers including acrylic, natural and/or synthetic rubberelastomers, ethylene vinyl acetate, polyurethane, and the like.

The adhesive layer or layers is applied to the opposing sides of thefoam layer in any convenient manner, e.g., spraying, dipping, rollcoating, dry or heat lamination, etc. The adhesive is applied in a verythin layer(s), e.g., between about 10 and about 100, preferably betweenabout 25 and about 75 and more preferably between about 45 and about 55,:m so as to provide a sufficiently strong bond between the foam layerand the film in one instance, and between the foam layer and a substratesurface in another instance.

Alternatively, a foam tape can be used in the construction of the label.A wide selection of foam tapes with pressure-sensitive adhesive layerspre-coated on each side is commonly available. One preferred foam tapeis Duplocoll 5016, a black polyethylene foam with a tackifiedsolvent-based acrylic pressure-sensitive adhesive coated on each sideand marketed by Lohmann.

In those embodiments in which a second adhesive layer is not an integralpart of the label construction, then the label must be affixed to asubstrate surface by other means, e.g., applying an adhesive to asubstrate surface to engage the label, use of mechanical means (e.g.,holders, friction fits, etc.), and the like.

For those embodiments of the invention in which a second adhesive is anintegral part of the construction of the label, then the label istypically carried on a release liner for storage and feeding through theprinter. The construction of the release liner is not particularlyimportant to the practice of this invention and its purpose, of course,is to protect the adhesive until the label is ready for application to asubstrate. The thickness of the release liner is typically between about25 and about 150, preferably between about 50 and about 150 and morepreferably between about 80 and about 120, :m. Examples of materialsthat can be used for the liner include glassine paper, laminated paper,polyester films and polypropylene film, preferably each of which hasbeen subject to a coating of silicone.

The composition of the coating used in the practice of this invention isalso not particularly important, and it typically comprises any materialthat can receive and hold an image from a printer or otherimage-transferring device, particularly a THT printer. Typically, thecoating comprises a layer made from a polymer that softens sufficientlyon heat application and offers sufficient adhesion to allow for goodtransfer of the ink layer from the THT printer during the printingprocess. Generally, coatings of this type can be formulated to soften atlower temperatures for best image formation, fast printing and lowerprinter wear, or to soften at higher temperature to achieve a moredurable, resistant image quality. Coatings for this purpose arecompounded from various polymers including polyesters, polyurethanes,polyolefins, acrylates, polyvinyl chloride, vinyl acetates, and thelike. These are sometimes compounded with other ingredients to supplythe correct abrasion resistance, slip characteristics, solventresistance, durability and handling through printers. The coating andfilm should be compatible with one another to ensure that their intimatecontact results in a strong and permanent bond between them. The coatingcan be applied to the film in any conventional manner.

The labels of this invention are prepared in a manner similar to thoselabels known in the art. In one illustrative method, the film is firstprepared in any conventional manner, e.g., cast or extruded, in one ormore multiple layers from one or more polymeric resins, e.g.,polyethylene terephthalate (PET). Many of the films used in the practiceof this invention are commercially available. The film is then coveredor coated (if a coating is part of the label construction) on one facialside, again in any conventional manner, with a printable coating. Afterthe coating is dried, the film is joined to the foam layer by the firstadhesive and if the foam layer contains a second adhesive on the sideopposite the first adhesive, then that is applied before this 4-layerconstruction is joined to a release liner by means of the secondadhesive layer (assuming that the label construction includes a secondadhesive; if it does not, then these last two steps are eliminated).

Many variations exist on this illustrative method of preparing the labelconstruction. For example, the two or more of the described steps can bereversed or otherwise changed in sequence, or the film and foamconstruction (with or without the coating) can be shaped or cut to aparticular size and/or design before or after applied to a release liner(assuming that a release liner is part of the ultimate labelconstruction), or, as noted above, a pre-constructed foam tape (with orwithout a release liner) can be joined to the film (with or without acoating), and the like. The final product is such that typically it canbe rolled upon itself for easy shipment and storage. The final productis used in the same manner with printers or other image-transferringdevices as are conventional labels, and are particularly useful with THTprinters, especially hand-held THT printers.

In another embodiment of the invention, the labels, i.e., constructionswithout a release liner, are placed upon the release liner in such amanner as to promote smooth operation of the printer or otherimage-transferring device, particularly a THT printer. In theseoperations, the release liner also serves as a carrier strip for feedingthe labels into and through the printer. The labels can be sized andshaped either before or after they are joined to the liner (usually thelabels are die cut while on the liner). Due to their thickness, eachlabel is typically separated from every other label on the strip, i.e.,they do not touch or abut one another; rather a gap or space existsbetween adjacent labels on the strip. This arrangement allows the stripto be folded or rolled onto itself for shipment, storage and/or tofollow the print track within the printer (which typically isserpentine).

As the strip carrying the labels passes through the space between theprint head/transfer ribbon and the platen roll, the print headexperiences considerable force away from the platen roll due to thecompression of the foam. When the label clears this space, the printhead has a natural tendency to recover to its normal position, and thiscan lead to printing problems such as either unprinted or partiallyprinted labels or even jamming of the print head against the strip whencontinuing to feed either in the forward or reverse (back-feed)direction. Several methods, alone or in combination with one or more ofthe other methods, have been identified to avoid, or at least reduce itsfrequency of occurrence, this problem.

One such method is spacing the labels on the release liner or carrierstrip at intervals from one another so that the print head does not havethe opportunity to push onto the carrier strip itself or, in otherwords, at least a number of labels are arranged on the strip such thatthe distance between adjacent labels is such that the platen roll doeslose positive frictional engagement with the carrier strip and the printhead does not lose contact with the printing surface of each label asone label leaves the printing station and another label enters theprinting station. This spacing is a function of the thickness of thelabels, the compressibility of the foam, and the diameter of the platenroller. The smaller the ratio of the diameter of the platen roller tothe thickness of the label, the smaller the spacing between the labelsmust be to prevent printing problems. The less compressible a giventhickness of the foam is, the smaller the spacing between the labelsmust also be to prevent jamming. FIG. 5 illustrates one embodiment ofthis spacing. The determination of other embodiments is within the skillof the ordinary artisan.

Another method is to include on the carrier strip support elements ofapproximately the same thickness as the labels, and to place thesesupport elements on the strip in such a manner as to prop the print headup while the carrier strip advances through the printer and positionsanother label for printing or, in other words, supporting elements arepositioned on the strip to bridge the space formed between twonon-abutting labels such that the platen roll does not lose positivefrictional engagement with the carrier strip and the print head does notlose contact with the printing surface of each label as one label leavesthe printing station and another label enters the printing station.These support elements are not labels, and are positioned so that theydo not receive an image from the transfer ribbon. FIGS. 6 and 7illustrate two such positions for these elements, i.e., between thelabels and between the labels and the long edge of the carrier strip,respectively. The size of the carrier elements can vary, but thepositioning and sizing of these elements is such to bridge the space orgap between adjacent labels on the carrier strip. Typically, the carrierelements are of the same construction of the labels, and are sized nolarger than necessary as to form an effective bridge between adjacentlabels.

The labels of this invention are used in the conventional manner. Ifcarried on a release liner and including a second adhesive that is apressure-sensitive adhesive, then after printing the label is removedfrom the release liner and applied with moderate pressure to a substratesurface, e.g., the face of an electrical panel or closet, such that theadhesive side of the label engages the substrate surface. If the labelconstruction does not include a release liner and/or pressure sensitiveadhesive, then after printing the label is simply affixed to thesubstrate surface by any convenient means, e.g., water or heat activatedadhesive, insertion in a label holder, mechanical fasteners, etc. Thelabels of this invention are particularly useful for identifying thevarious buttons and lights on electrical panels and closets and onceapplied to the panel or closet surface, they appear and feel as hardplastic identification shields.

Although the invention has been described in considerable detail, thisdetail is for the purpose of illustration. Many variations andmodifications can be made on the invention as described above withoutdeparting from the spirit and scope of the invention as described in theappended claims. All U.S. patents and allowed U.S. patent applicationsreferenced above are incorporated into the specification by reference.

What is claimed is:
 1. A method of printing labels in a thermal transferprinter configured for receiving and processing a labeling media havinga thickness of 300 microns or less, the printer comprising a print head,transfer ribbon and platen roll; the method comprising: feeding acarrier strip comprising a plurality of labels situated thereon throughthe printer, one or more of said labels being greater than 200 micronsin thickness and comprising a compressible foam material layer and aprintable substrate; wherein, as the carrier strip is fed through theprinter, the platen roll maintains positive frictional engagement withthe carrier strip, and the print head contacts the transfer ribbon toimprint an image on the printable substrate of said labels.
 2. Themethod of claim 1, wherein the foam material layer is at least 200microns in thickness.
 3. The method of claim 1, wherein at least twoadjacent labels situated on the carrier strip in a non-abuttingarrangement with a space therebetween.
 4. The method of claim 3, whereinthe space between the at least two adjacent labels is such that, duringfeeding of the carrier strip through the printer, the transfer ribbondoes not lose contact with the printable substrate of a label as itenters and passes through the printer.
 5. The method of claim 3, whereinthe space between the at least two adjacent labels is such that, duringfeeding of the carrier strip through the printer, the print head and thetransfer ribbon are not pressed into said space or onto the carrierstrip within said space.
 6. The method of claim 3, wherein the carrierstrip further comprises an element of about the same thickness as alabel positioned on the carrier strip such that the print head ispropped up while the carrier strip is fed through the printer.
 7. Themethod of claim 1, wherein the carrier strip further comprises a supportelement situated within the space between the at least two adjacentlabels, the support element not configured as a label.
 8. The method ofclaim 7, wherein the support element is sized smaller than the at leasttwo adjacent labels.
 9. The method of claim 7, wherein the supportelement bridges the space between the at least two adjacent labels. 10.The method of claim 1, wherein the carrier strip further comprises asupport element situated on the carrier strip between a label and a longedge of the carrier strip.
 11. The method of claim 1, wherein theprintable substrate of at least one of said labels comprises a polymericfilm.
 12. The method of claim 11, wherein the printable substratecomprises a polymeric coating on the polymeric film.
 13. The method ofclaim 1, wherein at least one label further comprises an adhesivematerial on a surface of the foam material layer.
 14. The method ofclaim 13, wherein the at least one label comprises a liner over saidadhesive material.
 15. The method of claim 1, further comprising, afterfeeding the carrier strip through the printer, forming the carrier stripinto a roll.
 16. The method of claim 1, wherein the printer is a thermaltransfer (THT) printer.
 17. The method of claim 1, further comprisingapplying an adhesive to a surface of the foam material layer and bondingthe printable substrate thereto.
 18. The method of claim 1, furthercomprising applying a coating to the printable substrate, said coatingcomprising a material for receiving an image from the printer thereon.